BRATTLEBORO, Vt. -- An Entergy Corp. lawyer argued Wednesday in the court battle over Vermont's refusal to extend the life of a nuclear power plant that state lawmakers wrongly considered safety in blocking an extension.

Kathleen Sullivan, an attorney for the New Orleans-based company, played dozens of audio clips in federal court from legislative committee discussions and floor debates to support Entergy's argument that Vermont legislators stymied the extension for Vermont Yankee in Vernon for the wrong reason.

Lawyers for both sides agree that federal law makes nuclear safety the sole province of the U.S. Nuclear Regulatory Commission. But the state argues that lawmakers used other reasons, including plant reliability and creating a better market for renewable energy, in voting down a bill that would have allowed state regulators authority to grant an extension.

U.S. District Judge J. Garvan Murtha heard the case without a jury. Wednesday was the third and final day. His ruling could some this fall.

The NRC approved a 20-year license extension for the plant earlier this year, but Vermont is the only state that also gives its Legislature such authority over power plants.

Sullivan told the judge the clips and legislative documents create "an astonishing legislative record," in which lawmakers knew they had to avoid safety as a reason for voting that the plant should close when its initial 40-year license expires next March, and some expressed frustration that they couldn't use what some around the Statehouse at the time called the "s-word."

But Assistant Attorney General Bridget Asay urged the judge not to focus on the conversations leading to passage of legislation, but the bills themselves. "What matters is the output," she said.

For the court to try to second-guess talks that occurred early in the development of legislation would not be consistent with "the deference courts give and should give" legislatures, Asay said.

Asay also came armed with audio clips and letters from Entergy executives and lobbyists that appeared to show the company acknowledging the Legislature had a key role to play in deciding the plant's future.

She pointed to an internal Entergy email in which executive vice president Curtis Hebert acknowledged that Vermont lawmakers had numerous concerns about Vermont Yankee aside from safety. The email was sent to CEO J. Wayne Leonard weeks after the Vermont Senate voted to block the state Public Service Board from issuing Entergy a new certificate so its plant could operate for 20 years past next March.

The Senate took that vote several weeks after learning that radioactive tritium was leaking from the plant and that plant executives misled lawmakers and regulators by saying the plant did not have the sort of underground piping that carried tritium.

"The evidence was clear that the testimony (on underground piping before the Public Service Board) had been incomplete, and this had a corrosive effect on our supporters throughout the state," Hebert wrote to Leonard.

Sullivan said the state was prohibited from considering the tritium leak because it, too, was a safety issue under the NRC's purview. She did not mention the mistrust many lawmakers felt following misleading statements from New Orleans-based Entergy.

One of the clips was of former Sen. Susan Bartlett, D-Lamoille, now a top aide to Gov. Peter Shumlin, who spoke of "an illegal discharge into the waters of the state. It's nuclear, which means we don't have any control over it, which truly makes me wild."

In an earlier debate on separate legislation allowing expanded nuclear waste storage at Vermont Yankee and imposing a new tax on the plant, then-Senate leader and now U.S. Rep. Peter Welch said: "Safety is the prime concern. Safety's not for sale. No amount of money is worth it to increase any risk of danger to Vermonters."

Many lawmakers were distrustful of the NRC and joined in a complaint long heard from nuclear skeptics that the federal agency is too close to the industry it regulates.

"I, as a matter of fact, trust the 180 people (Vermont legislators) up here with their limited knowledge a lot more than I trust the NRC in terms of their ability to act as an advocate for the population," Sen. Jeanette White, D-Windham, said in another of the clips.

Sullivan said lawmakers shied away from safety, even changing the word in a title of one bill from "safety" to "reliability," after she says they were coached by administration officials and consultants. Sullivan said lawmakers were essentially advised that "if you put safety too expressly into the bill, you're likely to be pre-empted."

But, she added, "You can take safety out of the title, but you can't take safety out of the purpose of the Legislation."